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300 Blackout (10.5″ SS Barrel & 10″ M-Lok Handguard) AR 15 – Complete Build Kit

$700.00 $600.00 (You Save $100.00)

300 Blackout (10.5" SS Barrel & 10" M-Lok Handguard) AR 15 - Complete Build Kit
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SKU: UA300PHB10.517(SS)-(10)MLOK_Budget


Our 10.5″ pistol upper chambered in .300 AAC blackout provides the perfect balance of compact profile and weight savings. The full-length M-LOK handguard is skeletonized and shaves off additional weight and offers some serious aesthetic appeal, while at the same time providing plenty of rail space for attachments. A free-float design further improves accuracy while a carbine gas system and 1:7 twist rate ensure this .300 blackout upper reliably handles supersonic and subsonic .300BLK loads. Topping it all off is an industry-leading 416R stainless barrel that makes this Pistol Upper perhaps the most accurate 300 Blackout Upper you’ll find in a pistol configuration.

The Most Accurate 300 Blackout Pistol Upper

The words “accuracy” and “pistol upper” don’t often go together, so we sought to fix that. We combined a best-of-both-worlds 10.5″ barrel length with a heavy profile and 416R stainless steel to offer the most accuracy possible. If there’s a .300 blackout pistol upper that might hit 1 MOA accuracy, you’re looking at it. Everything is manufactured under ISO 9002 quality control standards, and all rifling is CNC cut and heat-treated to a hardness rating of RC 28 to 32. This guarantees the most accurate barrel possible, with the most barrel life and wear resistance.

Assembling an 80% rifle kit is one of the fastest and most cost-effective ways to make yourself a proud new owner of an AR-15 rifle without registration, serialization, or an FFL purchase.

The lightweight 13.5″ M-Lok free-float rail allows scopes, tactical lights, hand grips, and many other accessories to be attached to your rifle quickly and efficiently. The AR 15 rifle kit is an ideal weekend project for build kit beginners. By the end of the weekend, you’ll ensure your family is safe with a finished, unserialized AR 15 rifle.


Gas System: Pistol-length
Barrel Profile: A2
Barrel Steel: 416R
Barrel Finish: Stainless
Chrome Lining: No
Muzzle Thread: 5/8×24
Chamber: .300BLK
Twist Rate: 1:7
Barrel Extension: M4
Gas Block Size: .750″
Gas Block Type: Low-profile
Muzzle Device: A2 Flash hider
Receiver Material: Forged 7075 T6
Receiver Type: M4
Handguard Type: 10″ lightweight M-Lok free float
Bolt Carrier Group Included: Yes
Bolt Steel: 9310 steel, magnetic particle inspected
Bolt Carrier Profile: Full-auto
Charging Handle Included: Yes

Benefits of the 10.5” Pistol-Length Nitride AR 15 Rifle Kit:

  • 100% legal to own and ship to your front door
  • Not considered a firearm – no FFL paperwork needed!
  • Stainless steel barrel and parts kit ensure sub-MOA accuracy
  • Prebuilt upper with gas system removes the guesswork of rifle making
  • Includes bolt carrier group, free-floated M-Lok handguard and lower parts kit

AR 15 Rifle Kit Details (Expanded):

Barrel: 10.5″ pistol-length stainless steel, chambered in .300BLK, 1:7 twist rate, .750″ low-profile gas block, 10″ free-float M-Lok handguard, with an A2 “birdcage” flash hider.

Upper Receiver Assembly: Forged from 7075 T6 aluminum, hard-coat anodized in black for durability, features M4 feed ramps, and are made in the USA.

Bolt Carrier Group: The bolt carrier is made from 9310 steel and has a staked gas key and black nitride finish. The bolt itself comes complete with an extractor spring and O-ring insert.  It accepts .223, 5.56mm, and .300BLK calibers (though you should NEVER attempt to use a caliber for which your rifle is not chambered), and is magnetic particle inspected.

80% Lower Receiver: Choose to receive a forged or billet Fire/Safe 80% lower receiver.  Our lower receivers are anodized to match the upper receiver perfectly. and they come ready for machining of the trigger pocket and drilling of the safety selector and trigger pin holes.

AR-15 Lower Parts Kit: includes all parts needed to complete the lower receiver including pistol grip, mil-spec safety selector, and trigger/fire control group.

Lower Parts Kit: Includes complete, mil-spec AR-15 parts kit. Features MOE trigger guard and Enhanced Polished Trigger (EPT).

Charging handle: Standard 7075 Forged charging handle.

Please note: This build kit requires that the builder complete the 80% lower receiver themselves, but that’s the rewarding part of the experience (and the only way to build your own AR-15 without the need of an FFL transfer or serialization).

No FFL required Made in the USA Lifetime Warranty

300 Blackout (10.5″ SS Barrel & 10″ M-Lok Handguard) AR 15 – Complete Build Kit

$700.00 $600.00 (You Save $100.00)

In stock

$700.00 $550.00 (You Save $150 )
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Free Shipping on all orders $325+!


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